Chinese officials say "homemade" explosives rocked two of China's top universities Tuesday, injuring nine people. Witnesses said one of the explosions left a smell of gunpowder. There have been no immediate claims of responsibility and no motive has been offered.

The first blast hit a cafeteria at Tsinghua University, just before noon, shattering many windows and filling one floor with smoke.

A university official, who refused to give her name, said six people suffered leg injuries and were taken to a hospital. A report by the official Xinhua News Agency said two of the injuries were "severe."

Ninety minutes later, another explosion struck nearby Peking University, which is widely known by its Chinese nickname, Bei-Da.

A Bei-Da official, who would only give his surname, Xu, said the blast injured three people. Mr. Xu refused to provide any further information, saying the matter was under investigation.

Tsinghua University is a prestigious school that counts Premier Zhu Rongji and Communist Party Chairman Hu Jintao among its graduates.

Both universities are located in the Northwest section of the Chinese capital.

There were no immediate theories about who was responsible for the explosions or what might have been behind them. There have been bomb attacks in China that the authorities have attributed to Muslim separatists, but bombs are also often used to settle personal or business disputes.

China bans almost all private gun ownership, but does less to regulate the explosives that are widely used in mining and other industries.